electromagnet stack with permanent magnet 2

Excuse my poor language.I live in France. My hobby is magnetic suspension/levitation. I would like to make a variable magnet very powerfull. Because the Joule effect in copper magnet wire I imagined to take a big permanent magnet 3"x3"N48 and to place it on the iron right core of a electromagnet. As it I have two magnets in série.Stacked. The big very powerfull permanent magnet and the electromagnet which will make the variable term of regulation and adjustement force. My problem is the design of the right electromagnet, the relationship between diameter/height and the profil of the core ( concentrator? conical? ...)and material of this core. This assembly is intended for magnetic suspension.Thank you for your help and for your advices to size the core and the windings. Thank you very much. Gilles

Hello Gilles,

I do not know magnets very well, but you might want to make a new post or edit this one because you used the "tips" (lihgt bulb) instead of the "question" (question mark) category.

People might not know that you are asking a question in this post with that heading.

One of the biggest problems in magnetic suspension is having stability. Usually this is achieved by using multiple coils instead of one large one.
Often high field electromagnet coils are wound with thin Cu strip and thin insulation between layers. You can get conductor cross section and still keep the windings close to the core.

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Rust never sleeps
Neither should your protection